1. Field of the Invention
The present invention pertains to a self-unloading truck trailer having a movable floor made up of segmented floor plates which are interconnected by hinge pins and are trained over drive and idler sprockets at opposite ends of the trailer body.
2. Background
In the art of self-unloading cargo handling trailers and truck bodies there have been several developments in an effort to provide a reliable and mechanically uncomplicated mechanism which is adapted to load and unload general cargo as well as bulk materials.
My U.S. Pat. Nos. 3,482,717 and 3,876,089 disclose and claim various improvements in continuous endless conveyor type floors for load hauling trailers and vehicle beds. However, it has been determined in the development of a self-unloading trailer which is suitable for loading, supporting and unloading various types of general cargo and bulk materials such as wood chips, gravel and other flowable materials that certain improvements are desired. As described in my earlier patent, a continuous belt type conveyor floor is desirable to minimize leakage when hauling bulk materials. However, a continuous flexible belt type member requires a substantial support floor for the load bearing portion of the belt, and the friction created between the belt and the floor is substantial. Moreover, when hauling bulk materials such as sand or gravel, inevitably a certain amount of material will become lodged between the conveyor belt and the support floor which can have damaging results to the bearing surfaces of the belt and the floor.
In my more recent patent (U.S. Pat. No. 3,876,089), the disadvantages of the earlier floor design were overcome somewhat with an endless conveyor made up of a series of overlapping slats which were provided with lugs interconnected by a continuous flexible cable and adapted to mesh with a drive sprocket and an idler sprocket disposed at opposite ends of the trailer body. The bearing friction problem of the earlier design was alleviated to some extent by the provision of a plurality of spaced apart elongated beams running lengthwise of the trailer bed and supporting the floor slats directly thereon. Although the self-unloading trailer disclosed in U.S. Pat. No. 3,876,089 was developed for handling bulk materials there were still problems associated with leakage of the material along the longitudinal edges of the moving floor and excessive bearing friction was still generated between the floor slats and the bearing rails.
Other configurations of movable endless conveyor type floors for haulage vehicles have included endless chains to which the floor slats are attached, which chains are trained over drive and idler sprockets similar to the sprockets described in my U.S. Pat. No. 3,876,089.
Several problems have remained in regard to the provision of a suitable self-unloading floor which may be adapted to general cargo type truck beds or trailers as well as for beds which are particularly adapted for hauling bulk materials. There is a further need to reduce the bearing friction between the movable floor and the floor bearing supports. The relatively heavy loads which must be endured by the floor and the bearing supports has created a rather vexatious problem in developing a suitable floor design. The endless chain or lug and cable type conveyor mechanisms are relatively expensive and subject to troublesome breakdowns. Moreover, there has been a need to adapt the continuous conveyor self-unloading floor to general cargo type trailers which may be used for hauling pallet or containerized cargo as well as bulk materials. It is to the abovementioned problems that the present invention addresses itself and provides solutions thereto resulting in improvements in self-unloading floors for transport vehicle beds and trailer units.